Hazelnut and Chocolate Cake

This is a recipe by chef Oren Becker, which was published in Hebrew on Ynet.
It appears there as a Passover recipe, but it's also a great gluten free recipe.

I made this cake initially without the topping, but it was a little dull-looking, so I added the ganache topping and then drizzled it with white chocolate to make it prettier.

Hazelnut and Chocolate Cake 

Ingredients (for one 10-inch cake): 

For the bottom layer: 
- 4 egg whites
- 10 tablespoons of sugar, divided into two sets of 5 tbsps each
- 1.5 cups (140 grams/ about 5 oz) hazelnuts
- 15 grams/about 0.5 oz walnuts, finely ground

For the second layer: 
- 240 grams/8 oz bittersweet chocolate
- 75 grams/2.5 oz unsalted butter
- 1/4 tsp instant coffee powder (optional)
- 4 eggs
- 8 tbsp sugar

For the Topping (optional): 
- 100 grams/3.5 oz bittersweet chocolate 
- 0.5 cups heavy cream
- 30 grams/1 oz white chocolate

Preparation: 

1. Line a 10 inch round cake pan (preferably a deep spring-pan) with parchment paper.  (This will make it easier to take the cake out at the end, although it isn't necessary). Preheat oven to 170 C/350 F.

2. Put the hazelnuts in a small pan and cook over a small flame for a few minutes until golden, or roast them in the oven for about 10 minutes until the same. Allow them to chill slightly and then grind them in a food processor. Combine with 5 tbsp of sugar and the ground walnuts.

3. Using a mixer, beat the egg whites with 5 tbsp of sugar until you get a stiff foam.

4. Gently fold the nut mixture into the foam. Pour the foam into the cake tin and even it out. Bake for about 15-20 minutes, until the cake is a deep golden color. Remove from the oven and immediately work on the next layer.

5. In a double boiler or in the microwave melt the dark chocolate (from the second layer ingredients) with the butter, until smooth. 

6. In a mixer beat the eggs, sugar and coffee until you get a stiff foam (this takes a while, since these aren't just yolks). 

7. Gently fold the egg foam into the chocolate until you get an even colored cream. Pour the chocolate cream over the first layer of cake and return to the oven for about 15 minutes. Remove from the oven and allow to cool completely.

You can serve the cake like this, but if you want to make it even richer and also more beautiful, you can create this ganache topping:
1. Heat the heavy cream to a boil and then pour over the dark chocolate (from the topping ingredients). Stir until the chocolate is fully melted. Pour the chocolate over the cake, even it out and then freeze for at least 30 minutes to allow the chocolate to set.

2. In a microwave-safe bowl melt the white chocolate until smooth (do it in 30 second increments). Using a fork drizzle the white chocolate over the ganache topping. Allow to set in freezer or refrigerator.

If you prepared the cake in a spring-form pan you can gently remove it from the pan to serve. If not, just serve in the pan.

Enjoy!